The present invention relates to a scanning electron microscope (SEM) capable of automatically imaging an arbitrary evaluation point on a specimen and a method therefore and more particularly, to an SEM apparatus having the function to create and determine an imaging recipe automatically from circuit design data without using an actual wafer and a method therefore, the imaging recipe being necessary for observing an arbitrary evaluation point with high image quality and high accuracy. Registered in the imaging recipe are imaging parameters such as coordinates of an imaging point, size/shape (of an imaging area associated the imaging point but will be simply referred to as imaging point size/shape in the following description), imaging sequence of imaging points each for addressing, auto-focus, auto-stigmatism or auto-brightness contrast, imaging position changing method and imaging conditions and templates of evaluation points or imaging points as well.
For formation of a wiring pattern on a semiconductor wafer, a method is adopted, according to which a coating material called resist is coated on the semiconductor wafer, a mask for light exposure of the wiring pattern (reticle) is superimposed on the resist and rays of visible light or ultraviolet light or an electron beam is irradiated from above the reticle to expose the resist to light, thus forming the wiring pattern. The thus obtained wiring pattern changes in its pattern shape with either the intensity the irradiated visible ray, ultraviolet ray or electron beam has or the aperture and therefore, for formation of a highly accurate wiring pattern, maturity of the result of pattern needs to be inspected. For the inspection, a critical dimension scanning electron microscope (CD-SEM) has hitherto been used widely. A dangerous or critically imperfect point on a semiconductor pattern to be inspected is observed as an evaluation point (hereinafter referred to as EP) with the SEM, so that various geometrically dimensional values including the wiring width and the like the pattern has can be measured from an observed image and the maturity of the result of the pattern can be evaluated on the basis of the thus measured dimensional values.
In order for the EP to be imaged with high picture quality without positional shift, part or all of imaging points including an addressing point (AP), an auto-focus point (AF), an auto-stigmatism point (AST) and an auto-brightness/contrast control point (ABCC) are set and at individual imaging points, addressing, auto-focus adjustment, auto-stigmatism adjustment and auto-brightness/contrast adjustment, respectively, are conducted. As regards the amount of shift of imaging position in the addressing, matching between an SEM image at a known coordinate AP registered as a registry template in advance and an SEM image observed in actual imaging sequence (actual imaging template) is examined and an amount of positional shift in the matching is estimated as an imaging positional shift amount in addressing. The aforementioned EP, AP, AF, AST and ABCC are collectively called imaging points and the coordinates of points including part or all of the imaging points, the size/shape of an imaging area associated with an imaging point (simply, the imaging point size/shape), the imaging sequence of imaging points and the imaging condition and the registry template as well are managed in the form of an imaging recipe. Conventionally, the imaging recipe has been created manually by an SEM operator, imposing a laborious and time consuming job on the operator. Further, for determination of individual imaging points and registration of a registry template in an imaging recipe, a wafer must be imaged actually at low magnification and hence the creation of imaging recipe is a factor responsible for a degraded operating rate of SEM. In addition, as miniaturization of the pattern advances, followed by introduction of, for example, a technique of OPC (optical proximity correction), the number of EP's subject to evaluation increases extravagantly and the manual creation of the imaging recipe is prone to be impractical.
Under the circumstances, a semiconductor inspection system is disclosed in JP-A-2002-328015 in which an AP is determined on the basis of semiconductor circuit design data (hereinafter referred to as CAD (computer aided design) data) described in, for example, GDS2 format and data at the AP is cut out of the CAD data so as to be registered as the registry template (hereinafter, the template created by cutting the CAD data will be referred to as a CAD data template) in an imaging recipe. In the system, any actual wafer need not be imaged only for the sake of determination of the AP and registration of the registry template and improvements in the operating rate of SEM can be realized. Then, when an SEM image at the AP is acquired in actual imaging sequence (called an actual imaging template), the system functions to perform matching between the actual imaging template and the CAD data template, reregister an SEM image corresponding to a position of the CAD data template as an SEM image template in the imaging recipe and thereafter cause the reregistered SEM image template to be used for an addressing process. The system further has a function to automatically detect a characteristic part of pattern from the CAD data and register it as the AP.